Specimen holder for comparators



May 2, 1950 B. FULLER I 2,506,493

SPECIMEN HOLDER FOR COMPARATORS Filed Feb. 28, 1946 3 elements which liein the beam of light will be infocus.

The form of the invention illustrated in Figures 5, 6, and 7 is similarin principle to the support hereinbefore described but is modified foruse in testing work pieces which have no flange by which they may besupported. Upon the base block It is mounted an upper block 62 which hasa plane upper surface 64 on which the work piece 66 may rest. A sideblock 68 is secured to one side of the block 62, this block rising abovethe top of the block 52 so as to provide a vertical plane of referenceIt against which may be pressed a pitch rod or wire 12. This pitch rodis vertically movable, the end portions thereof being disposed inrecesses in vertical blocks 14 and 16. The portion of the upper block 62remote from the side block 68 is beveled on its upper surface from acenter line to the front and rear edges as at 80 and 82 leaving acentral ridge 84 flush with the plane upper surface 64. This ridge 84furnishes a horizontal line exactly in the plane of focus of the opticalsystem so that a sharp shadow image of the ridge is thrown on the chart.A suitably placed horizontal line on the chart may be employed inconnection with. the shadow image of the ridge B4 to facilitate adjusting the holder to receive specimens for ex amination. If desired, asimilar vertical ridge 85 can be formed on the end face of the block 62by similar bevels as indicated in Figure 8, this ridge resulting in asharply focussed vertical. shadow image on the chart to be made tocoincide with a vertical line of reference on the chart. A back stop 88is provided for engagement by the work piece to focus the threadelements properly for projection of the shadow image on the chart.

The operation of this modified form of the support is similar to thathereinbefore described. The work piece 56 is placed upon the supportingsurface 64 and is pushed laterally against the pitch rod 12 and alsorearwardly against the back stop 86. The work piece is then manuallyrotated until the shadow image advances up or down sufliciently tocoincide as nearly as possible with the printed contour on the chart.

I claim:

1. A holder for a screw threaded object to be examined, comprising abase, a superstructure on said base having three plane surfacesperpendicular to one another for simultaneous engagement by a work pieceto determine a definite position of reference for work pieces to beexamined, a rod of a size to enter a thread valley of an object to beexamined and to engage the thread flanks approximately at the pitchdiameter of the thread, and means for holding said rod loosely againstone of said surfaces.

2. A holder for a screw threaded object to be examined, comprising abase, a superstructure on said base having a plane vertical wallsurface, a supporting member projecting horizontally from said wall andhaving a plane horizontal surface on which a work piece can rest, a rodof a siz to enter a thread valley of an object to be examined and toengage the thread flanks approximately at the pitch diameter of thethread, means loosely supporting said rod against said vertical Wallsurface, and a back stop member projecting from said wall and having aplane vertical surface which is perpendicular to the other two planesurfaces and is arranged for engagement by the thread crests of a workpiece suported by the holder for examination.

3. A holder for a flanged screw threaded object to be examined,comprising a base, a block secured on said base having a vertical planeWall surface on one side thereof, a rod of a size to enter a threadvalley of an object to be examined and to engage the thread flanksapproximately at the pitch diameter of the thread, means for looselysupporting said rod against said surface, a supporting plate secured onthe top of said block with spaced elements projecting beyond said sideof the block to receive the flange of an object to be supported forexamination, and a back stop member projecting from said block beneathone of said spaced elements for engagement by the thread of an objectsupported by said spaced elements.

4. A holder for a screw-threaded object to be examined, comprising abase, a superstructure on said base having a horizontal surface on whichsaid object is supported and two mutually perpendicular verticalsurfaces arranged to cooperate with said supporting surface to determinea definite position for said object, a rod having a diameter so relatedto the dimensions of the screw thread of said object that it can enter athread groove tangentially and engage the flanks thereof atapproximately the pitch diameter of the thread, and means for supportingsaid rod loosely in an approximately horizontal position against'one ofsaid vertical surfaces, wherebyi when an object to be examined issupported on said horizontal surface and is pressed laterally againstsaid rod, the rod bears against the adjacent vertical surface and theflanks of a thread valley and assumes the helix angle of the thread.-

5. A method of mounting on a comparator a screw-threaded object to beexamined, said method comprising resting said object on a horizontalsurface of reference with its axis of rotation perpendicular to saidsurface, pressing the object laterally toward a vertical surface ofreference, interposing between the screw thread and the said verticalreference surface a cylindrical rod which is free to move verticallythrough a limited range and which is of a size to engage the sides of athread valley at the pitch diameter of the object, and rotating theobject until one of the thread turns is at a point diametricallyopposite from the point of contact when said rod is at a predetermineddistance from said horizontal surface of reference, whereby thediametrically opposite thread is in observing, position. LEON B. FULLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,745,523 Beardsley Feb. 4, 19301,745,537- Hartness Feb. 4, 1950 1,761,260 Gallasch June 3, 1950

